Filter devices for accommodating filter elements are available on the market in a variety of embodiments. Such filter devices eliminate a not insignificant amount of the manufacturing cost for the design of the retaining device for releasably securing the filter element inside the respective housing as well as of the sealing device for sealing the interior of the filter element with respect to the filter housing.
With a filter device of the generic type defined in the introduction as disclosed in the DE 10 2004 029 225 A1, the screw connection has an internal thread incorporated directly into the housing cover into which an external thread can be screwed. The external thread is formed on a connecting piece protruding outward on the respective filter element. The sealing device is formed by an axially protruding sealing edge surrounding the connecting piece concentrically. This sealing edge forms the seal due to pressure applied to the sealing edge when the screw connection is tightened. This solution is problematical inasmuch as the security of the seal depends on the pressing force acting on the sealing edge, which requires strong tightening of the screw connection. This strong tightening leads to the requirement that the end cap of the filter element must be designed to have dimensional stability to prevent deformation of the end cap when the screw connection is tightened strongly. Problems arise in this regard with the usual design of end caps made of a plastic material.
DE 11 89 520 discloses a disposable filter for fluids. A replaceable filter element has an end cap designed for conducting fluid to the clean side as well as to the unfiltered side and can be disposed in a housing. The end cap can be screwed to a pipe connection on the filter housing. Furthermore, a peripheral sealing element is provided in a radially outer region between the filter housing and the end cap.
U.S. Pat. No. 4,719,012 discloses a screw-on disposable filter element. A sealing configuration provides a pipe connection for sealing the fluid connection from the inside of the filter element with respect to the pipe connection.